Transformer and regulators in heat transfer relationship



March 30, 1965 w. c. SEALEY 3,176,193

TRANSFORMER AND REGULATORS IN HEAT TRANSFER RELATIONSHIP Filed March 21, 1960 United States Patent M 3,176,193 TRANSFGRMER AND REGULATORS IN FEAT TRANSFER RELATIONSHW William C. Seaiey, Milwaukee, Wis, assignor to Allis- Chalmers Manufacturing (Iompany, Milwaukee, Wis. Filed Mar. 21, 1960, Ser. No. 16,582 6 Claims. (Cl. 317-103) This invention relates to an electrical power distribution system and in particular to substation equipment for use in a distribution system.

Electrical substation equipment broadly comprises two major components: transformers and regulators. One popular type of arrangement for substation equipment comprises a tank containing a transformer and mechanical load tap changing apparatus as an integral part of the transformer. Such a system is compact and may. be erected .on a single concrete mounting pad. On the other hand, the major disadvantage of this integral arrangenu at is that when an inspection or repair of the tap changing mechanism is needed the whole unit is put out of service.

Another popular method of arranging the transformers and regulators in substations is to treat each as a separate component in it own individual tank. Thus, in the prior art the transformer, which may be a three phase type, was mounted on its own mounting pad, generally a concrete slab. Likewise, the three single phase individually encased regulators used with the three phases of .the transformer were also placed on their own separate mounting pad. To permit keeping the units separate, overhead steel construction has been used for supporting the lines connecting the regulators and transformer at a safe elevation and for supporting the switch which bypasses the regulators from the transformer.

The advantages of maintaining the regulators and the transformers in separate tanks are numerous. For instance, such an arrangement offers flexibility through single phase regulation to substations having one outgoing feeder handling single phase loads on all three phases. It also makes available a convenient bypass switching arrangement which permits regulators to be bypassed for periodic inspection without interrupting transformer service. If necessary, a regulator can even be replaced Without interrupting service from the transformer. Separate regulator and transformer units also readily adapt to a utilitys expansion. A transformer may first be installed and when the load requirements of the transformer grow to such a degree as to require regulation, regulators can be added. The addition of such assembly line regulators is far less expensive than building a load ratio control unit into the previously installed transformer.

However, this type of system also has some disadvantages. The expense in constructing such a system where the regulators require one mounting pad and the transformer requires a second mounting pad is considerable. The overhead steel structure is another added expense and the space used by such a separated arrangement is also considerable. Among the reasons for mounting the transformer and regulators on two separate pads was the problem of dissipating heat from the surfaces of the transformer and regulators. A minimum of four feet separation has been generally accepted as a distance which will avoid a reduction of cooling of the transformer by the regulators. Decreased separation tends to cause a temperature rise in both units that exceeds the permissible 55 C. rise over ambient temperature set by the American Standards Association. Another reason that discouraged close mounting of the units was that the decreased separation hampered maintenance work and created difficulties in erecting the overhead bus structure.

3,176,193 Patented Mar. 30, 1965 Additional radiators, fins and baffles may be mounted on the units to minimize the heat dissipation problem that occurs if the units are closely mounted. However, these only add to the cost of the units and cause them to become non-standard items thereby creating a production problem. Considerable time and effort has been spent by those in the transformer field in developing methods for operating transformers at overloads without materially affecting the life of the transformer. Use has been made of the fact that transformers operate several degrees cooler outdoors than when tested indoors due to the increased air movement. This heat problem is not as critical in regulators since they seldom stay long at their extreme tap positions where the .copper losses in the form of heat are the greatest. Thus, regulators usually operate at much lower temperatures than transformers.

The economical system of this invention overcomes the heat problems involved in the prior art and provides the advantages of both the integral type arrangement and the separated arrangement through the mounting of individually tanked regulators to the tank of a transformer.

It is therefore one object of this invention to provide for a new and improved electrical power distribution system.

A second object of this invention is to provide for a new and improved compact substation unit.

Other objects and advantages of the present invention are apparent from the following description when read in connection with the accompanying drawing in which the figure is a perspective view of the apparatus.

As illustrated in the figure, substation unit 11 includes a separately tanked transformer 12 of the three phase variety and three separately tanked regulators 13, 14 and 15, one regulator for each of the three phases. As illustrated, only one foundation slab or mounting pad 17 is needed to support the transformer and regulators. In fact, the regulators can be supported solely by the transformer and need not rest on the pad. The three tanked single phase regulators are mounted directly on transformer tank 19 by means of brackets 21 which are of a substantial heat conducting material such as metal. A conventional bypass switch 22 for each of the single phase regulators is also mounted on the transformer tank 19 directly above the regulators. The purpose for making brackets 21 with a substantially theat conducting material is to establish a thermal flow between the transformer and the regulators. As mentioned above, the problem of heat dissipation from a transformer is well recognized. Furthermore, a transformer inherently operates with a higher oil temperature than a regulator because a regulator has maximum copper loss, which is a major heat contributing factor, only near the minimum buck and boost positions even at full load. The regulator has nearly zero copper loss near its natural position. Thus, this inherent feature of the regulators operating at a lower temperature than that of the transformer provides for transfer of heat from the transformer to the regulator.

The advantage of this unique system i that the removed heat is put to a useful purpose by directing it to the regulators 13, 14 and 15. As heat flows into the regulators, the oil contained in each regulator tank is heated, thereby enabling the mechanical tap changing equipment to operate more smoothly and efliciently. This advantage is particularly desirable when the substation unit 11 is operated in extremely cold areas which cause the oil to become substantially viscous. The transferred heat tends to increase the flow or fluidity of the oil thereby allowing the mechanism in the regulators to operate more smoohtly with less friction. Another advantage of transferring heat in the transformer to the regulaarmies tors is the reduction of condensation in the air space at the top of the regulator tanks 24. Condensation occurs quite frequently in electrical apparatus containing oil since covers 25 and tanks 2d enclosing the regulating apparatus have a temperature which sometimes becomes lower than the air temperature. Therefore, if the temperature of regulator tank covers 25 can be maintained nearer that of the air temperature or'even greater, the likelihood of condensation in the air space at the top of the tank is considerably reduced. in order to more fully achieve thi advantage, the support brackets 21 used to connect the transformer and regulator tanks may be mounted near the top of the regulator tanks where condensation is most likely. By also mounting the regulators close to the transformer, the possibility of wind currents dissipating the flow of heat through the brackets to te regulators i reduced. This lack of space about the regulators is not a problem in inspecting the units since they may be of the type that are jacked directly upward from their tanks. For even better heat conduction it is possible that the brackets include a metal band encircling each of the regulators. Another alternative is to make the brackets of a hollow configuration thereby providing an enclosed connected air space between each of the regulator tanks and the transformer tank. When the temperature of the regulators and transformer are close together movement of the air in the passages of the mounting brackets can be assisted by opening thermostatically controlled louvers or using fans for allowing the forced air from the transformer fans to enter the enclostr Thus, it can be seen that there are a number of advantages obtained by mounting a separately encased regulator to the side of a transformer tank. The cost in erecting the substation unit is reduced by eliminating the ordinarily required overhead steel structure and second mounting pad. Less fioor space is also required. The mechanical tap changing equipment is able to operate in a lower and more nearly constant viscosity oil and there is also substantial reduction of moisture condensation in the regulator tanks. Thus, in addition to keeping benefits of both the integral type construction and the individually mounted arrangement, it is apparent that additional advantages are obtained through the above described system.

It is apparent that the invention is not limited to the particular features of design and construction described herein and shown in the drawing, and that the invention includes such other forms and modifications as are embraced within the scope of the annexed claims.

Having now particularly described and ascertained the nature of my said invention and the manner in which it is to be performed, I declare that what I claim is:

1. An electrical power distribution system comprising a transformer, said transformer enclosed in a tank, a load tap changing regulator enclosed in a second tank, and a support element secured to said regulator tank and said transformer tank intermediate their ends and spaced from the ground, said support element being of a heat conducting material whereby a thermal ilow occurs between said tanks.

2. An electrical power distribution system comprising a-transformer enclosed in a tank, a load tap changing regulator enclosed in a second tank and substantially submerged in oil, anda support element secured to said regulator tank and said transformer tank intermediate their ends and spaced from the ground, said support element being of a heat conducting material whereby a thermal flow occurs between said tanks.

3. An electrical power distribution system comprising a transformer, said transformer enclosed in a tank resting on a foundation slab, a load tap changing regulator enclosed in a second tank and substantially submerged in oil, and a supportelernent secured to said regulator tank and said. transformer tank with said regulator tank resting on said foundation slab, said support element being spaced from said slab and of a heat conducting material whereby a thermal flow occur between said tanks.

4. An electrical power distribution system comprising a transformer enclosed in a tank, a vertically mounted load tap changing regulator enclosed in a second tank and substantially submerged in oil, and a support element secured to said tank and upper third of said regulator tank, said support element being of a heat conducting material whereby a thermal flow occur between said tanks.

5. An electrical power distribution system comprising a transformer, said transformer enclosed in a tank resting on a foundation slab, a load tap changing regulator enclosed in a second tank and substantially submerged in oil, switching means mounted on said transformer tank for electrically removing said regulator from said distribution s stem, and a support element secured to said regulator tank and said transformer tank, said support element being spaced from said slab and of a heat conducting material whereby a thermal flow occurs between said tanks.

6. An electrical power distribution system comprising a three phase power transformer, said transformer enclosed in a tank resting on a foundation slab, three single phase load tap changing regulators, each said regulator 7 being enclosed in an individual tank and substantially submerged in oil, switching means mounted on said transformer tank for electrically removing said regulators from said distribution system, and support elements slecured to each said regulator tank and said transformer tank with said regulator tanks resting on said foundation slab, said support elements being spaced from said slab and of a heat conducting material whereby a thermal flow occurs between said transformer tank and said regulator tanks.

References tilted by the Examiner UNITED STATES PATENTS JOHN F. BURNS, Primary Examiner. i

torn MecoLLUr/i, SAMUEL BERNSTelN, Examiners. 

1. AN ELECTRICAL POWER DISTRIBUTIONN SYSTEM COMPRISING A TRANSFORMER, SAID TRANSFORMER ENCLOSED IN A TANK, A LOAD TAP CHANGING REGULATOR ENCLOSED IN A SECOND TANK, AND A SUPPORT ELEMENT SECURED TO SAID REGULATOR TANK AND SAID TRANSFORMER TANK INTERMEDIATE THEIR ENDS AND SPACED FROM THE GROUND, SAID SUPPORT ELEMENT BEING OF A HEAT CONDUCTING MATERIAL WHEREBY A THERMAL FLOW OCCURS BETWEEN SAID TANKS. 